1. Field of the Invention
The present invention relates to an image forming apparatus, and more specifically relates to an image forming apparatus for facsimile machines, printers and the like provided with a detection device to detect the number of remaining sheets.
2. Description of the Related Art
Conventional facsimile machines are provided with a paper near-empty detection device which detects and displays the number of remaining recording sheets when the number of said sheets becomes low, and a paper empty detection device which detects and displays the lack of recording sheets when no sheets are remaining. When the aforesaid paper empty detection device detects a low number of remaining recording sheets, a display or like warning assures that an operator replenishes the recording paper. When the aforesaid paper empty detection device detects a lack of recording paper, facsimile machines provided with a memory for storing reception data are capable of storing in said memory the received image data, such that the image data stored in memory may be printed after the recording paper is replenished. When the aforesaid paper empty detection device detects a lack of recording paper, facsimile machines which are not provided with a memory interrupt the reception operation until the recording paper is replenished.
When the aforesaid facsimile machines which are not provided with a memory run out of recording paper while printing a multi-page document such that the reception operation is interrupted, a signal indicating an abnormal situation is sent to the transmitting source machine. While the aforesaid printing operation is interrupted, only the document printed prior to said interruption of the printing operation can be removed. Typically, multi-page documents have the sender's name written only on the cover sheet, such that when a document printed prior to the interruption of the printing operation is removed, it becomes unclear who the sender is after the recording paper has been replenished and the remainder of the document has been printed.
The paper near-empty device for facsimile machines which use single cut sheets as the recording paper detects the position of a lifting plate upon which are disposed the copy sheets. It is difficult to accurately measure the position of the aforesaid lifting plate in the near-empty detection device, such that there is some variance as to the quantity of remaining sheets when a near empty condition is detected. Thus, in order to accurately detect the quantity of remaining sheets, a high-precision detection means must be provided to detect said quantity of remaining sheets, thereby further increasing the complexity of the overall apparatus. That is, it is extremely difficult to easily and accurately detect the quantity of remaining sheets with conventional sheet detecting devices.